I don't know why, but in case you missed it, they put the instructions in the PU natural listing instead of the rinse agent.
You've got 6 hrs before it hardens up. Throw a red rinse cartridge in after work, which should stop the reactant in the remaining PUR, then follow with 3 pucks of EVA to clear out that mixed junk. I haven't had personal experience with it though, since the cleaning scares me